Method and apparatus for drying treatment of solids in the fluidized or gas entrained state



Nov. 13, 1956 R. MORRISON 2,770,052

METHOD AND. APPARATUS FOR DRYING TREATMENT OF SOLIDS IN THE FLUIDIZED ORGAS ENTRAINED STATE Filed July 29, 1952 4 Sheets-Sheet 1 ow N I I! OINVENTOR. L N Roberr L.Morrison BY 0Z4 ATTORNEY 4 Sheets-Sheet 2 m d-u m1956 R. L. MORRISON METHOD AND APPARATUS FOR DRYING TREATMENT OF SOLIDSIN THE FLUIDIZED 0R GAS ENTRAINED STATE Filed July 29. 1952 INVENTOR.Robert L. Morrison ATTORN EY 2,770,052 ENT OF SOLIDS Nov. 13, 1956 R. L.MORRISON METHOD AND APPARATUS FOR DRYING TREATM IN THE FLUIDIZED OR GASENTRAINED STATE Filed July 29, 1952 4 Sheets-Sheet 5 INVENTOR. Robert L.Morrison fifa 7 Zw ATTO R N E r' Nov. 13, 1956 R. L. MORRISON 2,770,052

METHOD AND APPARATUS RYING TREATMENT OF souns IN THE FLUIDIZ GASENTRAINED STATE Filed July 29, 1952 4 Sheets-Sheet 4 ATTORNEY UnitedStates Patent Robert Laurance Morrison, Blairrnore, Alberta, Canada,assignor to Silver Engineering Works, Inc., a division of the SilverCorporation, a corporation of Colorado Application July 29, 1952, SerialNo. 301,494

8 Claims. (Cl. 34-10) This invention relates to fluidized orgas-entrained drying of solid materials, and is particularly suited fora drying treatment of coal having a relatively high percentage ofsurface or inherent moisture. I

Treatments for the drying of coal in the fluidized state have been thesubject of considerable study by the U. S. Bureau of Mines and theresults of these studies have been disclosed in the patent applicationof Vernon F. Parry, Serial No. 111,752, filed August 22, 1949, forContinuous Process for Devolatilization of Carbonaceous Materials, etc.,now U. S. Patent No. 2,666,269, issued January 19, 1954. Such treatmentshave involved the reduction of the coal or other fuel to finely dividedcondition, after which it is fed into a heating chamber where it isentrained in a rising column of heated gas and is moved at a controlledrate to bring the temperature of the solids to a predetermined point,thus limiting the heating interval and effecting a maximum removal ofmoisture without destructive distillation of the coal.

The present invention represents improvements over prior practice in themethod of introducing the fuel and entraining the materials beingprocessed and in the control of combustion. While the invention will bedescribed with particular reference to treatments involving the removalof surface or inherent moisture from fine coal, it should be understoodthat it is generally applicable to the treatment of any kind ofsubdivided material, such as coal, vermiculite, ore concentrates,sludges, beet pulp or the like.

It is an object of the present invention to provide a simple, economicaland efficient process for the removal of surface or inherent moisturefrom materials in finely divided condition.

Another object of the present invention is to provide a method ofcontrol of the entrainment stage by which coal or the like is conductedthrough a drying treatment in a fluidized or gas-entrained state.

A further object of the invention is to provide a simple, durable andefficient mechanism for the entrainment of coal or the like in afluidized or gas-entrained state preparatory to drying.

Still another object of the invention is to provide a simple, economicaland efficient mechanism for classifying solids in the drying column.

Another object of this invention is to provide a novel control of thecombustion stage of the operation.

Other objects reside in novel details of construction and novelcombinations and arrangements of parts, all of which will be set forthin the following description.

The practice of the invention will be best understood by reference tothe accompanying drawings. In the drawings, in the several views ofwhich like parts have been designated similarly,

Fig. 1 is a schematic representation in front elevation of a typicalplant installation embodying features of the present invention;

Fig. 2 is a fragmentary front elevation, partially broken to showinterior parts, ofthe furnace and mixing zone "ice of the plant assemblyshown in Fig. 1, and drawn to an enlarged scale;

Fig. 3 is a section taken along the line 33, Fig. 2;

Fig. 4 is a fragmentary section of the extractor unit for removal ofcoal from the pressurized mixing zone shown in Fig. 2;

Fig. 5 is a fragmentary front elevation, partially broken to showinterior parts, of the drying column and fuel feeding mechanism of theplant assembly shown in Fig. 1, and drawn to an enlarged scale;

Fig. 6 is a section taken along the line 66, Fig. 5;

Fig. 7 is a section taken along the line 77, Fig. 5;

Fig. 8 is a section taken along the line 88, Fig. 5;

Fig. 9 is a section taken along the line 9-9, Fig. 8;

Fig. 10 is a vertical central section through a pressure valve orfeeding device of the type shown in Fig. 1; and Fig. 11 is a sectiontaken along the line 11-11, Fig. 10.

The plant assembly shown in Fig. 1 comprises a storage bin or receptacle20, from which the stored material such as coal, is moved by an agitatorunit 21 into a feeding device 22, both of which are driven by a motor 23through the intermediary of transmission systems 24 and 25. The materialis discharged by the feeding device 22 into a. drying column 26intermediate the limits of its vertical extent. The base of the columnis supported on a mixing chamber 27 forming an extension of the furnaceunit 28 and having a sump portion 29 for the removal of oversizematerial, as will be set forth in the following description.

The vertical column 26 terminates at its upper end in an extensionconduit 31, which delivers the fluidized material and associated gasesand vapors into a primary separator unit 32, preferably of the cycloneseparator type, from which gases and suspended solids travel through atop outlet 33 to a point of division 34, with one stream of the gas withsuspended material passing into a dust separator 35, whilethe remainderis drawnby a fan 36 through another duct or conduit 37 to constitute thesupply for a recirculating gas main duct 38 discharging into the lowerportion of furnace 28 for mixing in chamber 27.

A suitable damper or valve 39 directs a portion of the flow in duct 38upwardly through a conduit 41 having a damper control 40 supplying aheader 42 mounted on the top of furnace 28, and a series of downwardlydirected ports or outlets 43 discharge the recirculated gases along theinner walls of the furnace to insulate them from excessive heating, thusretarding the formation of slag. A blower or fan 44 supplies air througha line 45 into the top entrance of furnace 28 and a second line 46extending from the blower receives the solids discharge of dustseparator 35 through a feeder or valve 47 and the resulting mixtureconstitutes one of the fuel supplies of furnace 28. Additional fuel,which may be oil, gas or added pulverized fuel, is delivered through aheader or line 48 into the top entrance of furnace 28.

The separated solids of primary separator 32 descend into an outlet line49 and are discharged therefrom by a pressure valve or feeder 51 onto aconveyor 52 which conducts them to storage or point of use. Thisdischarge represents the dried coal or material recovery of the systemand is in condition for use as a dried product at the time of discharge.

With this understanding of the general plant arrangement and operation,various novel details and operations of the present invention will bedescribed. The mixing chamber 27 of this invention is preferablysupported on suitable structure such as a series of beams 53 (Fig. 2)and has an insulated bottom 54 separated by a ventilation space from thefoundationSS. The main duct 38 enters the furnace 28 adjacent its bottomand extends into an inspirator unit 56 so arranged as to provide aventuri passage for products of combustion travelling from furnace 28 tomixing chamber 27. A baffle 57 positioned forwardly from the dischargeend of duct 38 imparts an upward component of movement to the resultingmixture of products of combustion and recirculating gas in mixingchamber 27 and accelerates the flow of the mixture into entrance 58 atthe bottom of column 26. This bafile also provides a quiescent zone forcollection of oversize material.

Solids which are too heavy to entrain in the rising gases descend fromcolumn 26 into sump 29, as do other solids from furnace 28 which areswept over baffle 57 but are not entrained in the vertically risinggases. A screw conveyor 59 or other conveying means moves thesecollected solids through the sump to a discharge outlet 60 (Fig. 4)controlled by a pressure valve 61. A thermocouple 62 is provided at thebottom of column 26 for controlling the mixed gas temperature bycontrolling the damper 39 and therefore controlling the quantity ofrecycled gases entering the mixing chamber 27.

Referring next to Figs. 5 through 9, a material such as bituminouscoking coal having from 5% to 25% surface moisture is stored in bin 28,and the agitator 21 at the bottom of the bin breaks up consolidatedmasses and delivers the coal in loose condition into the screw conveyoror feeding device 22. Suitable manholes or service openings 63 may beprovided in this device.

The screw discharges the conveyed coal onto a suspended screen'64 and aseries of agitator blades 65 are disposed above screen 64 within column26 to facilitate the discharge through the screen openings and over thesides and end of the screen. Part of the coal is entrained immediatelyabove the screen by gases passing upwardly through the screen holes.This action produces a reasonably uniform distribution of the productthroughout the area of the column, and entrained solids will risereadily through and around the screen and agitator blades in theirascent through the column.

The mixed gases entering column 26 through entrance 58 are firstsubjected to a swirling effect by a vane assembly 67. In order to getthedesired swirling eifect with the least loss of pressure, the individualvanes (Fig. 9) have a vertical portion 68, a curved intermediate portion69, and an upper inclined portion 70. A series of baffles 72 in radialarrangement are positioned above the vane assembly 67 to break up theswirling effect. This arrangement of vanes and baffles establishes apressure or velocity equalization across the area of the drying columnwhich facilitates entrainment. In this way proper control of theentraining action can be maintained. The individual particles are sothoroughly dispersed in the gaseous portion that all their surfaces arebrought into repeated and intimate contact with the rising gases.

The swirling vanes can be arranged at a suitable angle to give aclassifying effect on the material to be dried, with the oversizeparticles descending into sump 29, while lighter solids are readilyentrained and pass upwardly in column 26.

Solids falling as agglomerated masses on the vane structure are brokenup on such vane structure and there-. after are subjected to theaforesaid entraining or classifying effects.

The fluidized or gas-entrained fuel has attained the desired reductionin moisture content by the time it reaches the primary separator 32 andis subjected to a gas-solids separation therein. The separated gasespassing out through outlet 33 carry minor quantities of. fine dust.Since fuel is a requirement of the treatment, these solids are separatedin dust separator 35 and delivered into the furnace 28 as part of thefuel supply thereto.

The dried coal settling in dust separator 35 descends through itsconical bottom portion to enter an outlet passage 50, the discharge ofwhich is controlled by the pressure valve or feeder device 47 (valve 47is structurally similar to valve 51 and both are similarly operated),the details and functioning of which will now be described. This valvecomprises an intermediate cylindrical body portion 75 and a flanged,tubular inlet 76 and a flanged tubularoutlet 77. The inner-cylindricalportion comprises an inner and outer annulus 78 and 79 respectively,both of which are stationary and an intermediate annulus 81 which isrotary.

The outer annulus has an entrance opening 82 which aligns with inlet76,and an outlet passage 83 at 180 from opening 82. The rotary annulus 81is provided with a series'ofopenings: 84 which move in register withentrance opening 82 toreceive coal from inlet 76. The side walls ofcylindrical portion 75 'are journalled as shown at 85a and 85b forreception of a shaft 86 which imparts the rotation toannulus 81 througha hub 90 adapted to be held on shaft 86, and a plate 91 connects annulus81 and hub 98. An opening 87 is provided for admission of a pressurefluid into the interior of annulus 78, which fluid flowing throughopening 88 forces the descending coal through opening 83 whenever one ofthe openings 84 aligns therewith and the companion opening 77 of theoutlet passage.

This arrangement maintains sufficient pressure in the interior ofannulus 78 to provide a positive discharge of the solids against thepressure flow in line 46, while permitting a combined gravity-mechanicalfeeding to insure an adequate supply of solids within the enclosure.After discharge from valve 47, the solids descend into line 46 and passto furnace 28.

In a typical operation, the mixture of coal and gas usually reaches afinal temperature of from 250 F. to 350 F. before discharging intoprimary separator 32. The volume of the passage from the furnace outletto the primary separator is a factor of residence time and wherematerials of relatively high moisture content are being treated, apreferred arrangement is to enlarge the,

vertical column .as indicated by dotted lines 26x in Fig. l to provide alonger residence time.

It is towbe understood that the practices and plant ar:

' rangement previously described are intended to teach the practice ofthe present invention, but not to limit same, and changes andmodifications may-be availed of within the spirit and scope of thisinvention.

I claim: 1

1. In apparatus for-drying subdivided materials in a fluidized orgas-entrained state, an upright drying column, means for introducingheated gases into the lower end of said column, means for introducingsubdivided material intosaid column above its bottom, a swirl-impartingmeans in the column intermediate said points of introduction havingsurfaces arranged to impart a centrifugal movement to the enteringgases, and vertical 'bafile meansin said column intermediate said pointsof introduction and above and spacedfrom said swirl-imparting means toretard the centrifugal movement.

2. Iii-apparatus for drying subdivided materials in a fluidized orgas-entrained state, an upright drying column, means for introducingheated gases into the lower end of said column, meansforiintroducingmaterial in subdivided condition into said column above its bottom, aseries of spaced vanes in the column intermediate said points ofintroduction having surfaces arranged to impart'a centrifugal movementto the entering gases, and a series of vertical baffles in the columnintermediate said points of introduction andabove'and spaced from saidvanes for retarding the centrifugalmovement.

3. In apparatus for drying materials in a fluidized or gas-entrainedstate, an upright drying column, means for introducing-'heatedgases intothe lower end of said column, means for introducing material insubdivided condition into said column above its bottom, a swirlimpartingmeans in thecolurnn-intermediate said points of introduction to impart acentrifugal movement to the entering gases and arranged to impart aclassifying effect in the material, and baflle means in the columnintermediate said points of introduction and above said vanes forarresting the centrifugal movement and resulting material classifyingaction.

4. In apparatus for drying subdivided materials in a fluidized orgas-entrained state, an upright drying column, means for introducingheated gases into the lower end of said column, and a feeding device forintroducing subdivided material into said column intermediate its ends,including a screen member of curved section having an open top and anopen end extending substantially across the interior of the column, andagitators for breaking up lumps and moving the subdivided materialthrough the screen openings and over the top and end so as to dischargethe material over a substantial area of the column.

5. In apparatus for drying subdivided materials in a fluidized orgas-entrained state, an upright drying column, means for introducingheated gases into the lower end of said column, and a feeding device forintroducing subdivided material into said column intermediate its ends,including a material supporting surface having an open top and an openend extending into said column and an agitator mechanism for breaking uplumps and discharging the feed over the edges of said surface and over asubstantial area of the column.

6. The process of drying sub-divided coal or the like, which comprisesdirecting heated gases upwardly through a closed vertical drying zone,feeding such coal in subdivided condition into said drying zoneintermediate its ends, subjecting the heated gases to a swirling actionat the lower end of said drying zone and below the level of feedintroduction, subjecting the swirling gases to a swirl-retarding actionat a point below the level of feed introduction to the drying zonewhereby the coal is suspended in the non-swirling gas, and separatingthe dried coal from heated gases after its passage from said dryingzone.

7. In apparatus for drying subdivided materials in a fluidized orgas-entrained state, a furnace having walls defining a combustion zoneand provided with a fuel inlet at one end and a discharge for heatedgases at an opposite end, conductive means for returning cooled,circulated gases of the drying treatment to the furnace and a series ofspaced ports at the inlet end of the furnace arranged to receive anddischarge the recirculated gases adjacent to and along the interiorwalls of the furnace in the direction of the discharge end, whereby toinsulate said walls from excessive heating and slag formation.

8. In apparatus for drying subdivided materials in a fluidized orgas-entrained state, a furnace having walls defining a combustion zone,conductive means for returning cooled circulated gases of the dryingtreatment to the furnace, and a series of laterally spaced conduitsarranged to receive the recirculated gases and having downwardlydirected outlets adjacent to and along the inner upright walls of thefurnace, whereby to insulate said walls from excessive heating and slagformation.

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